The use of polymeric materials in concrete formulations is well known. One common composite material is called polymer-impregnated concrete (PIC) wherein hardened portland cement concrete is impregnated with a liquid monomeric material which is subsequently polymerized in situ. These materials have remarkable durability and resistance against salts and the like which make their use especially attractive for concrete pipe, desalting plants, tunnel support linings and bridge decks. Another system is a polymer-portland cement concrete (PPCC) which is produced by adding a monomeric or polymeric material to a fresh portland cement concrete mixture which is subsequently cured and polymerized after placement. It will be appreciated that both the PIC and PPCC systems are hydraulic systems, i.e., they require the use of water to cure the portland cement. Accordingly, another system has more recently been dicovered which is called polymer concrete (PC) which contains little or no cement and no water. The PC is a composite formed by polymerizing a monomeric material with aggregate (gravel, sand, etc.).
The resin most often employed in present PC compositions are the so-called acrylate resins, especially, methyl methacrylate. These acrylate resins are relatively inexpensive; however, they suffer a multitude of serious shortcomings. For example, they exhibit high volatility, high toxicity, high flammability, and are explosive. More importantly, they exhibit high shrinkage which severely limits their useful life in some applications.
A number of the serious environmental shortcomings (toxicity, volatility, etc.) can be eliminated by the replacement of the methacrylate resins with polyester resins in combination with an aggregate composition containing fly ash. This unexpected and novel improvement is disclosed and claimed in copending patent application Ser. No. 250,990, filed Apr. 3, 1981. While the compositions of Ser. No. 250,990, reduced the number of environmental shortcomings of the non-fly ash methacrylate PC systems, the resulting PC compositions, while exhibiting improved physical properties, still exhibit too high shrinkage for many applications.
A novel PC composition has now been discovered which exhibits improved physical and chemical properties, especially reduced shrinkage after cure.